Electric-motor starter.



W. e. OBRBN.

ELECTRIC MOTOR STARTER.

APPLICATION FILED SEPT. 10, 1906.

990,035, Patented Sept. 29, 1908. n

To all 'whom it may concern:

Baltimore, Vin the State of Maryland, have linvented certain new and useful Improvesliding contacts.

1 current'is turned on; Fi 2 is a similar view I electric motor and S indicates the line switch section R2 of starting resistance, 'switchconmotor acquires speed, without the use of coils b of a solenoid B, a section R of starting and'D are verticali arranged so that their 'l towards the liixed contacts 6, 7 and 8r'espec-v tively arranged beneath tlie cores.l and each UNITED STATES PATENT OFFICE.

WILLIAM C. OBRIEN, OF BALTIMORE, MARYLAND, ASSIGNOR TO MONITOR MANUFACTURING COMPANY OF BALTIMORE'CITY, OF BALTIMORE, MARYLAND, A CORPORATION OF MARY- LAND.

ELEC'.IRIC--MOTORy STARTER.

I Specification of Letters Patent. A i APatented Sept. 29,19%. v

Original application filed. October 23, 1905, Serial No. 284,105. Divided and. this application lecl September 10, 1906.

'serial No.

Be it known that I., WILLIAM C. O'BRIEN, a citizen ofthe United. States, residing at ments in `Electric-Motor Starters, of which the following is a speciiication.

The purpose of this invention is to provide an automatic starter for electric motors which will operate to cut out the starting resistance from the armature circuit as' the dash pots or mechanical retarding devices, orv

This application is a dlvision' of my copending application, Serial N o. 284,105, filed October 23rd, 1905.

In the accompanying drawin Figure 1 is a view showing diagrammatica ly a starter made according to my invention, the parts being shown in their normal positions in full manner in whichthe solenoid cores, which cut out the startino resistance, are released from the mechanical holding means when the showing the positions o the parts after the current has been turned on and al1 ofthe resistance has been cut out exce t one section.

Referring to the drawings il indicates an for connecting the starter and motor with the line circuit L L. The motor shown in the drawings is shunt wound, the field circuit extending from the line switch terminal 1 through conductor 2 and motor iield]r to the return wire 3 and thence to the line switch terminal 4. The armature circuit 5, a's shown in the drawing, is connected to line terminal-1 through conductor 2 and extends l from said conductor successively through the resistance, switch contact ,16, the coil c' of a solenoid C, asection R ofstarting resistance, ,Switch contact 7, 'coils'l d of a solenoid. D, a

tact 8, armature a and conductor 3 to the line terminal 4. rIhe regulating .solenoids B, C

cores 9, 10 and 1 1 wi l tend to dropv by gravity core preferablyhasatits lower end a 'swivtrical Vcontact with the iixed 4contact piece beneath it when the core drops.` The cores are connected by flexible conductors 12, 13 and 14, respectively, to the' conductor 2 and by said conductor to the line terminal 1. The iiexible conductors 12, 13 and 14 might be connected directly to the shoes s, but for `conveniencethey are connectedto the rods 9a, 10'L and 11a respectively, 'of non-magnetic metal, which are secured to the upper ends of the cors, and the flexible conductors,y

the rods andthe cores for'mshunt circuits which short circuit the solenoid coils and the' resistance'steps when the cores are down a'nd the shoes s rest upon the stationary contacts.

The cores constitute the movable members of switches t, t and t and the contacts 6,

eled section or. shoe s for making good elec- 7 and 8 are the opposing members of the".

switches. These switches are normallyheld in the open positions, shown in Fig. 1, by bell crank levers c, f and g, having their .longer arms hinged to a rod 15, and their shorter arms extending beneath collars 16,

17 and-18 upon the rods which projectupwardly from the ends of the solenoid cores. The bell crank lever e has an extra arm 19 u on which is suspended the core 20 of a hol ing solenoid vH. The cores andthe levers are so proportioned Vthat the core 20 will overhalance the weight of the cores 9, 1() and 11, and

for this purpose the core 20 may be weighted at its. lower.end, as indicated at '20a'. The solenoid H, as shown in the drawing, has

windings h connected to the line switch terminals 1 and 4 by conductors 21 and 22, so that each time the lineswitch is closed the core 20 will be instantly raised, and when the line switch is o ened the core 2 0 will drop.

When t 1e line switch is in open position, as shown in Fig. 1, the cores of solenoids B, O and D are held in their upper positions, and as the switches t, t .and t are then open the winding-s of these solenoids and the resistance sections are lall inv series with the armature. The armature circuit, it will -be noted, is never interrupted between the line. switch andthe motor. As soon as the hne .switchis closed the lsolenoid H. attracts its core, and thus the bell crank levers are at once thrown into the position shown in dotted lines in Fig.A 1 and in full lines in Fig.

. 2 but thestarting Ycurrent in? the armature position.

llevers have been moved downward. These solenoids are arranged so that their cores will drop in succession as the current in the armature circuit decreases. For this purpose l have shown the collar 16 heavier than the collar 17, and the latter heavier than the collar 1S, so that the cores of the solenoids are,diii`erently weighted and with similar windings the cores will drop in succession, from leftA to right in the drawing, as the current decreases by reason of the acceleration of the motor armature, in starting. When the current falls to a certain predetermined extent, the core Q drops, thus closing the switch t and the current then iiows trom the line terminal 1 and condutor 2 through flexible conductor 12, core 9 and contact 6 to the conductor 5 and thence through the successive solenoids and resistance sections to the armature. The closing of the switch t, causes the coils oi solenoid B and the resistance section R to be short circuited. Witha further decrease in the starting current the core ofA solenoid C will drop, closing the switch t, and-the current will then pass through ileXible conductor 13, core 10 and contact 7 to the conductor 5 and thence through solenoid D and resistance section R2 to the motor. The coils of'solenoid C and the section R of the resistance will therefore be cut out. In Fig. 2 the parts are in their `position just described, the cores,9 and l() being down and the core 11 still in its upper Vith a still further fall in vthe starting current, Vdue to the acceleration of the armature, the core of solenoid D will drop and short circuit its coils and the resistance section R2, the current then passing through i'lcxible conductor 14, core 11 and -contact 8, and from thence through conductor 5 directly to the motor. All of the resistance sections and the solenoid coils will then be cut out. This4 cutting out of the resistance sections takes place at a rate which is approximately proportional to the fall of current in the armature circuit and to the acceleration of the armature. 'If the motor starts quickly the solenoid cores dro in succession quickly; but if the motor is eavily loaded and starts slowly the cores will be held longer in their upper positions.

When the line switchis opened, the solenoid H is thereby denergized, and its core 20 drops downward, causing the bell crank levers to rock and lift-the cores of the solenoids B, C and D, thus opening the switches t, t and t and thereby reinserting the starting resistance and the solenoid windings in the armaturecircuit. These switches ior o ening and closing the shunt circuits aroun the y resistance sections and solenoid coils, it will be noted are operated in both. directions by gravity, the cores 9, 1.0 and 11 being raised by Jthe Weight of the core 20 when the currentis cut oil', and moving to their closed positions by their own weightwhen the mechanical supports are removed and the current in the armature circuit falls to normal.

Nhat I claim is- 1. In an automatic starter.' for electric motors, a starting resistance for the armature circuit, a regulating device having windings in said circuit and having a core or armature, a switch for cutting out said resistance, said switch being normally open and movable by said core or armature to closed position, electro-magnetic holding means having a core or armature, and connections between said cores or armatures whereby the core or armature of the holding mean's serves as a means for normally overbalanemg the core or armature of the regulating device to permit the switch to remain open, saidv holding means being arranged to retract its core or armature when current is turned on.

2. ln. an automatic starter for electric motors, a starting resistance for the armature circuit, and a series oi regulating devices each having windings in said circuit and each havinga core or armature, switches for cutting out said resistance andwindings, said switches being normally open and movable by said cores or armatures to closed position, an electromagnetic holding device having a core or armature, and oo nnectionsbetween said cores whereby the core or armature of the holding device serves as a means ior normally overbalancing the cores or armatures of the several regulating'devices to permit the switches to remain open, said holding device being arranged to retract its core or armature-when current is turned on.

3. ln an automatic starter for electric motors, a starting resistance in the armature circuit, a regulating solenoid having windings in said circuit, a switch for short-circuiting said resistance and windings, said switch being connected to the core `ot said solenoid ,and movable therewith by gravity toclosed position,v a lever movable independently of said. core and adapted to move said core to open the switch, and a holding solenoid having a core connected to said lever and adapted to overbalance the core of the regulating solenoid and hold said latter core with the switch in open position, said holding solenoid being adapted to move the lever so as to release the core of the regulating solenoid when the current is turned on. y

et. In an automaticstarter for electric motors, a starting resistance in the armature circuit,va plurality of regulating solen- 'oids having windings in said circuit, switches for short-circuiting said. resistance and windings, said switches being connected to the cores of said solenoids, and movable therewith by gravity'to closed position, a lever movable independently of said cores and l the lever so as to release the cores of the regumeans connected With the lever for moving lai-ting solenoids when current is turned on. 10 said cores to open the switches, and a holding .In testimony whereof I aiix my signature, solenoid having a core connected to said lever in presence of two Witnesses.

and adapted to overbelaneeV the cores of the WILLIAM C. OBRIEN. regulating solenoids and hold said latter j Witnesses: eores with the switches in open positions, M. WARNER HEWES, Jr., said holding solenoid being adapted to move JoHN W. HEWES. 

